1 research outputs found
Linking Load, Fuel, and Emission Controls to Photochemical Production of Secondary Organic Aerosol from a Diesel Engine
Diesel engines are important sources
of fine particle pollution
in urban environments, but their contribution to the atmospheric formation
of secondary organic aerosol (SOA) is not well constrained. We investigated
direct emissions of primary organic aerosol (POA) and photochemical
production of SOA from a diesel engine using an oxidation flow reactor
(OFR). In less than a day of simulated atmospheric aging, SOA production
exceeded POA emissions by an order of magnitude or more. Efficient
combustion at higher engine loads coupled to the removal of SOA precursors
and particle emissions by aftertreatment systems reduced POA emission
factors by an order of magnitude and SOA production factors by factors
of 2–10. The only exception was that the retrofitted aftertreatment
did not reduce SOA production at idle loads where exhaust temperatures
were low enough to limit removal of SOA precursors in the oxidation
catalyst. Use of biodiesel resulted in nearly identical POA and SOA
compared to diesel. The effective SOA yield of diesel exhaust was
similar to that of unburned diesel fuel. While OFRs can help study
the multiday evolution, at low particle concentrations OFRs may not
allow for complete gas/particle partitioning and bias the potential
of precursors to form SOA